Having a male partner who is violent increases the risk of acquiring HIV for women in rural South Africa, researchers reported.

Action Points

Explain to interested patients that observations have suggested that male violence and being in an unequal relationship are risk factors for women to acquire HIV.

Note that this analysis, the first from a randomized trial, confirms the observations.

Having a male partner who is violent increases the risk of acquiring HIV for women in rural South Africa, researchers reported.

And gender-based power inequity in a relationship also increases the risk of acquiring the virus, according to Rachel Jewkes, MD, of the Medical Research Council in Pretoria, South Africa, and colleagues.

The two factors together "account for a substantial proportion of HIV infections," Jewkes and colleagues concluded in their report online in The Lancet.

Their findings are consistent with earlier research and observation, but are the first to come from a prospective randomized trial, Jewkes and colleagues noted.

The researchers estimated that some 11.9% of new HIV infections -- the so-called population attributable fraction -- could be prevented if women did not experience more than one episode of physical or sexual partner violence.

By the same token, they said, 13.9% of incident HIV could be avoided if no women were in relationships in which they had low power.

The findings bring "clarity to the probable relation of male partner violence to HIV infection," said Jay Silverman, PhD, of Harvard School of Public Health in Boston, writing in an accompanying commentary in the journal.

And they show, for the first time, that male violence precedes HIV infection in their female partners, he said.

One implication of the study, Silverman said, is that interventions aimed at reducing risky behavior in abusive men are "probably insufficient" to cut the risk of transmission. Instead, he argued, "altering the gender-based abusive behaviors of men has been called for."

There is some evidence -- from a small randomized trial -- that such interventions might work, Silverman said.

Jewkes and colleagues reported data collected during a randomized trial of a 50-hour program of sexual and reproductive health and HIV education, delivered to 1,415 women ages 15 to 26 between 2002 and 2003 in 70 rural locations in South Africa.

For this longitudinal analysis, the researchers excluded 316 women who had HIV at the start of the trial, had missing data, or were lost to follow-up. The 1,099 women included in the analysis were initially HIV-negative andhad at least one subsequent HIV test during the 24 months after entering the trial.

Power within a sexual relationship was measured using a 10-point questionnaire; intimate partner violence was measured using the World Health Organization's nine-item instrument that examines both physical and sexual violence.

For the analysis, women in the lowest tertile of power in their relationships were compared with those in the middle and highest groups; women who reported more than one episode of sexual or physical violence were compared with those who reported one or none.

Overall, 128 women were infected with HIV during 2,076 person-years of follow-up, for an incidence rate of 6.2 per 100 person-years, the researchers found.

However, 45 of the 253 women who reported more than one episode of intimate partner violence at baseline were infected, for an incidence rate of 9.6 per 100 person-years.

In contrast, 83 of the 846 who reported one or no episodes became infected, for an incidence rate of 5.2 per 100 person-years.

The adjusted multivariable incidence rate ratio was 1.51, with a 95% confidence interval from 1.04 to 2.21, which was significant at P=0.032, Jewkes and colleagues reported.

Findings were similar for relationship inequity, they said. Some 51 of the 325 women with low relationship power equity at baseline were infected, compared with 73 of the 704 women with medium or high relationship power equity.

The incidence rates were 8.5 and 5.5 per 100 person-years, respectively, yielding an adjusted multivariable incidence rate ratio of 1.51, with a 95% confidence interval from 1.05 to 2.17, which was significant at P=0.027.

The researchers cautioned that there's no evidence that intervening to reduce women's exposure to violence reduces their risk of getting HIV and said such studies "should be a priority."

The study was supported by the National Institute of Mental Health and the South African Medical Research Council.